1. Field of the Invention
The present invention relates to power management, and more particularly to a control circuit of the power management.
2. Description of the Related Art
FIG. 1 shows a traditional approach for controlling an alternating current (AC) power to a load. FIG. 2 shows a waveform of the circuit in FIG. 1. The AC power line VAC is applied to terminal L and N of a power line, which connected to a load 95. A circuit including a thyristor 90 and a phase controller 92 is connected to the power line. The waveform of the power line signal VTR is shown in FIG. 2. The phase modulation controller 92 controls the thyristor 90 to achieve a phase modulation to the power line signal VTR. The disadvantages of this traditional approach lie in poor power and high input current harmonic, which causes a high power loss for power transmission. The present invention provides a method and an apparatus to solve this drawback. The proposed interface through the AC power line can be used for ceiling fan control, dimming control of lighting, and so on.